ES2745578T3 - Steam boiler system and procedure to control a steam boiler system - Google Patents

Abstract

Steam boiler system (1) comprising: - a steam boiler (5) that generates steam from the feed water; - a condenser (2; 42) that transfers heat from said steam to said feed water; - a first feed water line (3) connecting said condenser (2; 42) to a feed water source (4) to supply feed water to said condenser (2; 42); - a second feed water line (6) connecting said condenser (2) to said steam boiler (5) to feed feed water from said condenser (2) to said steam boiler (5); - a first steam duct (8; 48) connecting said steam boiler (5) and said condenser (2; 42) to supply steam to said condenser (2; 42) from said steam boiler (5); - a condensate tank (22) arranged to collect the condensate generated from said steam in said condenser (2; 42); - a first condensate duct (14) connecting said condensate tank (22) to a tempering unit (13); said boiler system (1) further comprising: - a second condensate duct (15) connected to said condensate tank (22) and directly to a steam drum (24) in said steam boiler (5) to feed condensate outside said condensate tank (22) and inside said steam drum (24); - a first regulating valve (19) arranged to regulate the flow of condensate through said second condensate line (15); - an economizer unit (9) connected to the second feed water pipe (6) between said steam boiler (5) and said condenser (2; 42); - at least one temperature sensor (26) adapted to measure at least one parameter indicative of the temperature of the supply water in the second supply water conduit (6); - a control unit (18) adapted to control said first regulating valve (19) at least partially depending on the information collected by said temperature sensor (26); and - at least one condensate level sensor (20; 44) adapted to measure at least one parameter indicative of the level of condensate in the condensate tank (22), - said control unit (18) is coupled to at least one temperature sensor (26) and at least one condensate level sensor (20; 44); said control unit (18) being adapted to control said first regulating valve (19) at least partially based on the information collected by said condensate level sensor (20; 44).

Description

DESCRIPTION

Steam boiler system and procedure to control a steam boiler system

Subject of the invention

The present invention is described in claim 1 and relates to a steam boiler system comprising a steam boiler to generate steam from the feed water and a condenser to transfer heat from the steam to the feed water. The steam boiler system further comprises a first feed water line to connect the condenser to a feed water source to supply feed water to the condenser, a second feed water line that connects the condenser to the steam boiler to supply feed water from the condenser to the steam boiler and a first steam line connecting the steam boiler and the condenser to supply steam to the condenser from the steam boiler. The steam boiler system also comprises a condensate tank arranged to collect the steam-generated condensate in the condenser and a first condensate line to connect the condensate tank to a tempering unit.

The invention is also described in claim 3 and also relates to a method for controlling a steam boiler system, which steam boiler system comprises a steam boiler, a condenser, a first feed water line to connect the condenser to a feed water source, a second feed water line connecting the condenser to the steam boiler, a first steam line connecting the steam boiler and the condenser, a condensate tank and a first line line to connect the condensate tank to a tempering unit. The procedure comprises the steps of supplying feed water to the condenser through the first feed water line, supplying feed water from the condenser to the steam boiler through the second feed water line, using the steam boiler to generate steam from the feed water, supply steam from the steam boiler to the condenser through the first steam duct, use the condenser to transfer heat from the steam to the feed water to preheat the feed water and generate steam condensate, and collect the condensate in the condensate tank.

Background of the Invention

A steam boiler system comprises a steam boiler adapted to vaporize feed water to generate steam. Steam can be used for many different purposes, for example to generate rotary motion in a turbine.

It is preferable to use steam boiler systems with high thermal efficiency. One way to increase the thermal efficiency of a steam boiler system is to incorporate superheaters into the system. The saturated steam from the steam boiler is guided through the superheaters to generate superheated steam with high internal energy. Superheated steam is also more likely to remain above the condensation temperature of water vapor, reducing the risk of corrosion damage to the boiler system and any applications connected to it.

Advantageously, the temperature of the superheated steam is regulated by one or more desuperheaters arranged between the superheaters. Desuperheaters ensure that the temperature of the superheated steam remains within a predetermined range. A common type of desuperheater is the spray water desuperheater. The spray water desuperheater uses spray water to regulate the temperature of the superheated steam.

It is important to use pure spray water to avoid contamination from superheated steam. GB 686,008 refers to a process for producing condensate for use as spray water in a desuperheater. The saturated steam produced in a boiler is guided to a condenser, in which the feed water supplied from a feed water tank is used as a refrigerant for the generation of condensate from the saturated steam. The condensate is collected in a condensate tank and either delivered to the desuperheater or returned to the feed water tank. This system is known as the Dolezal spray water tempering system.

Another way to increase the thermal efficiency of a steam boiler system is to preheat the feed water before it enters the steam drum. For example, the use of one or more economizers to preheat feed water is known. A common type of economizer uses hot gases resulting from the combustion of the steam boiler to preheat the feed water. A problem associated with this type of economizer is that a low feed water temperature can cause dew point corrosion damage in the economizer. Dew point corrosion occurs when acids and corrosive compounds from the flue gases condense on the heating surfaces of the economizer. US2012 / 255303 A1 and GB 686054 A also describe prior art steam boilers.

Object of the invention

A first object of the invention is to provide a compact and thermally efficient steam boiler system. A second object of the invention is to provide a method for the efficient control of said steam boiler system.

Definitions

The expression "connected to, connected to" does not always mean directly connected to. The connected elements can be connected by means of intermediate elements.

A "steam boiler", as defined herein, comprises a steam drum in which steam and water are separated from the boiler. The steam drum may be arranged adjacent one or more parts of the steam boiler, for example an oven, or at a distance from the other parts of the steam boiler. A "conduit" is a suitable device for transporting a fluid. A duct may consist of a single element or comprise a plurality of connected elements.

The water that flows from a source of feed water to the steam drum is called "feed water" while the water flowing in the steam boiler through the steam drum and the boiler water pipes is called "boiler water".

Brief description of the invention

The first object of the invention is achieved with a boiler system as defined in the preamble of the present application. The boiler system according to the invention further comprises a second condensate line connected to the condensate tank to feed the condensate out of the condensate tank and a first regulating valve arranged to regulate the flow of condensate through the second condensate line.

The first regulating valve allows adjustment of the condensate level in the condensate tank, so that the condensate level can be controlled independently of the condensate flow through the first condensate line arranged to supply condensate to the tempering unit.

A condenser according to the invention comprises an internal supply water conduit system comprising at least one internal supply water conduit connecting the first and second supply water conduits. The internal feed water line system extends at least partially through a condensate reservoir, in which the surfaces of the internal feed water line system can be exposed to steam from the steam boiler, so that the Heat from the steam is transferred to the feed water that flows through the internal feed water conduction system. The condensate tank is also arranged to collect the condensate generated by the steam. The higher the level of condensate in the condensate tank, the smaller the surface of the internal feed water conduction system exposed to the steam and the lower the rate of heat transfer from the steam to the feed water. This means that the level of condensate in the condensate tank can be used to regulate the rate of heat transfer in the condenser. Consequently, independent control of the level of condensate in the condensate tank allows independent heat transfer control and, therefore, allows independent control of the temperature of the feed water leaving the condenser. Therefore, the condenser in the steam boiler system according to the invention acts not only as a means of supplying condensate to the tempering unit, but also as a means of preheating and regulating the temperature of the feed water. This enables a compact and thermally efficient steam boiler system.

One or more condensate tanks can be connected to the second condensate line between the first regulating valve and the condensate tank in the condenser. That is, each condensate tank is connected to the condensate tank and is arranged to collect the condensate from the condenser.

The first regulating valve is properly connected to the second condensate line. However, the first regulating valve may also be connected to a separate means connected to the second condensate line, said separate means being adapted to guide the condensate to or from the second condensate line.

The fact that the steam boiler system according to the invention allows independent control of the feed water temperature in the second feed water line makes it suitable for use with an economizer unit. The economizer unit is properly connected to the second feed water line between the steam boiler and the condenser. An economizer unit according to the invention can comprise any number of economizers. Independent control of the level of condensate in the condensate tank ensures that the temperature of the feed water entering the economizer unit is maintained above a predetermined lower temperature. This ensures that no dew point corrosion occurs in the economizer unit. The temperature of the feed water entering the economizer unit can also be kept below a predetermined higher temperature to minimize the risk of steam generation in the economizer, i.e. the rate of heat transfer from the steam to the feed water at the condenser can be reduced when the temperature of the feed water in the second feed water line approaches the predetermined upper temperature.

Advantageously, the steam boiler system comprises at least one temperature sensor adapted to measure at least one parameter indicative of the temperature of the feed water in the second feed water line, and a control unit coupled to the fuel sensor. temperature and to the first regulating valve, which control unit is adapted to control the first regulating valve, at least partially, depending on the information collected by the temperature sensor. In those embodiments where the boiler system comprises an economizer unit, the feed water temperature is preferably measured at a point upstream and / or near the entrance to the economizer unit.

Advantageously, the steam boiler system comprises at least one condensate level sensor adapted to measure at least one parameter indicative of the level of condensate in the condensate tank, and the control unit is advantageously adapted to control the first regulating valve at least partially based on the information collected by the condensate level sensor. Suitable condensate level sensors are, for example, hydrostatic pressure sensors and radar level sensors.

Advantageously, the steam boiler system comprises at least one of said temperature sensors and at least one of said condensate level sensors, and the control unit is advantageously adapted to collect information from both sensors and use that information to control the first regulating valve.

The second condensate line and the first regulating valve are used to regulate the level of condensate in the condensate tank. The second condensate line may be arranged to conduct condensate from the condensate reservoir to one or more parts of the steam boiler system and / or outside of the steam boiler system. For example, the second condensate line can be arranged to supply condensate to the steam boiler, preferably to the steam drum in the steam boiler. This embodiment is advantageous in that it allows a reduction in the flow of feed water from the feed water source to the steam drum. The second condensate line can also be arranged to conduct the condensate to the source of the feed water. The second condensate line can also be arranged to guide part of the condensate to the steam boiler and part of the condensate to the source of feed water.

The bottom of the condensate tank is advantageously arranged so that the condensate can flow by gravity to the indicated part (s) of the steam boiler system or out of the steam boiler system. For example, the condensate tank is advantageously located on the steam drum in the steam boiler when the second condensate line is arranged to guide the condensate from the condensate tank to the steam drum. It is also possible to use one or more pumps to move the condensate through the second condensate line.

The second condensate line is advantageously connected to the bottom or near the bottom of the condensate tank. This arrangement increases the scope of the condensate level.

The boiler system according to the invention is particularly suitable for use with a spray water tempering unit, since the condensed water is pure enough to be injected as a coolant into the superheated steam. However, the invention is also compatible with other types of tempering units.

The steam boiler system can comprise more than one condenser. These condensers can be arranged in many different ways in the steam boiler system and use separate or common ducts, control units, regulating valves and sensors.

In one embodiment, the steam boiler system comprises two condensers connected to the same boiler of steam by means of separate first steam ducts. Condensers are connected to the same first and second feed water lines and to the same first and second condensate lines. The steam boiler system may comprise a single first regulating valve arranged to regulate the flow of condensate to the condensers or two first regulating valves, each first regulating valve being adapted to regulate the flow of condensate from a respective condenser.

The second object of the invention is achieved with a method for controlling a steam boiler system as defined in the preamble of the present application. The method further comprises the step of controlling a flow of condensate from the condensate tank through a second condensate line connected to the condensate tank by means of a first regulating valve.

As mentioned above, this arrangement allows independent control of the feed water temperature in the second feed water line and therefore allows efficient control of a compact and thermally efficient steam boiler system in the that the condenser also acts as a preheater for the feed water.

Advantageously, the method comprises the step of regulating the flow of condensate through the second condensate line to ensure that the temperature of the feed water at a specific point in the second feed water line is maintained above a temperature bottom default. This stage is particularly advantageous when the steam boiler system comprises an economizer unit connected to the second feed water line between the condenser and the steam boiler, since it ensures that the temperature of the feed water entering the economizer unit is maintained above a temperature that can cause dew point corrosion in the economizer unit.

The method may also comprise the step of regulating the flow of condensate through the second condensate line to ensure that the temperature of the feed water at said specific point in the second feed water line is kept below a predetermined higher temperature. . When the measured temperature of the feed water in the second feed water line approaches the predetermined upper temperature, the control unit uses the first regulating valve to increase the level of condensate in the condensate tank and thus reduce the speed of heat transfer in the condenser. This embodiment is particularly advantageous when the steam boiler system comprises an economizer unit connected to the second feed water line, since it reduces the risk of boiling in the economizer unit.

In these embodiments, the temperature is advantageously measured at a point upstream and / or near the entrance to the economizer unit.

The method may also comprise the step of regulating the flow of condensate through said second condensate line to ensure that the level of condensate in the condensate tank is maintained within a predetermined range. For example, it may be desirable to ensure that the level of condensate in the condensate tank remains above a minimum level to ensure that there is sufficient condensate in the condensate tank for the tempering unit. It may also be desirable to ensure that the condensate level remains below a predetermined maximum level, to ensure that some part of the internal feedwater conduction system remains exposed and therefore maintains at least a minimum transfer rate. of heat in the condenser.

Advantageously, the method comprises the steps of continuously measuring at least one parameter indicative of the temperature of the feed water in the second feed water line, and controlling the first regulating valve at least partially depending on the parameter values. measured. This stage allows precise and automated control of the feed water temperature in the second feed water line. In those embodiments where the second feed water line is connected to an economizer unit, the temperature is advantageously measured at a point upstream and / or near the entrance to the economizer unit.

Advantageously, the method comprises the steps of continuously measuring at least one parameter indicative of the level of condensate in the condensate tank and controlling the first regulating valve at least partially as a function of said values of the measured parameters. These measurements can be used to ensure that the condensate level remains within a predetermined range.

In some embodiments, the steam boiler system may comprise more than one sensor, and the sensors may be adapted to measure a plurality of different parameters. For example, the method may comprise the steps of continuously measuring the level of condensate in the condensate tank and the temperature in the second feed water line and adjusting the first regulating valve at least in part based on information received from one or both sensors.

The method may also comprise the step of guiding the condensate through the second condensate line to one or more suitable parts inside and / or outside the steam boiler system, for example to the steam boiler, to the water source of supply and / or to a separate condensate tank connected to the supply water source.

The steam boiler system according to the invention comprises at least one of each duct. The person skilled in the art understands that a single conduit can be replaced by two or more conduits that have the same purpose. For example, more than one first supply water line can be used to connect the condenser to the supply water source and more than one second supply water line can be used to connect the condenser to the steam boiler. It is also possible to use more than the first steam line to connect the steam boiler and condenser and to use more than a second condensate line (and therefore more than a first regulating valve) to connect the condensate tank with a or more parts of the steam boiler system and / or the feed water source.

The person skilled in the art also understands that additional ducts and devices can be connected to the steam boiler system according to the invention.

Drawings

The invention will now be described with reference to the following drawings, in which similar numbers are used to designate similar characteristics and in which:

Figure 1 is a schematic drawing of a first embodiment of a steam boiler system according to the invention;

Figure 2 is a schematic side view of a condenser in the steam boiler system of Figure 1;

Figure 3 is a schematic drawing of a second embodiment of a steam boiler system according to the invention;

Figure 4 is a schematic drawing of a third embodiment of a steam boiler system according to the invention.

Detailed description of the invention

Figure 1 shows a first embodiment of the steam boiler system 1 according to the invention.

The boiler system 1 comprises a condenser 2 and a first feed water line 3 for connecting the condenser to a feed water source 4. The feed water is supplied by means of a feed water pump 27 from the source of feed water 4 to condenser 2 through the first feed water line 3.

The feed water flows through an internal feed water conduction system 7 in the condenser 2 and from there to a steam boiler 5 through a second feed water line 6. The feed water is preheated in condenser 2 by means of a saturated steam flow from steam boiler 5 through a first steam line 8 to condenser 2.

An economizer unit 9 is connected to the second feed water line 6 between the steam boiler 5 and the condenser 2. In this embodiment, the economizer unit 9 comprises a first and a second economizer 9a, 9b. In alternative embodiments, economizer unit 9 may comprise a single economizer or more than two economizers. The economizer unit 9 uses hot combustion gases from the steam boiler 5 to raise the temperature of the feed water flowing through it. The flue gases are supplied through a flue gas line 10.

The feed water can be preheated in condenser 2 to ensure that the acids and corrosive compounds in the flue gases do not condense when the flue gases are cooled in the economizer unit 9. If possible, the temperature of the feed water also it is maintained at a temperature below a predetermined higher temperature to reduce the risk of boiling in the economizer unit 9. That is, the rate of heat transfer from the steam to the feed water in the condenser can be reduced if the water temperature of the The feed in the second feed water line is approaching the predetermined upper temperature.

Thereafter, the feed water is fed to a steam drum 24 in the steam boiler 5. The steam boiler 5 further comprises an oven (not shown) and a network of boiler water pipes (not shown) connected to the steam drum 24 and arranged so that the boiler water flowing through the boiler water pipes can absorb the heat generated by burning fuel in the furnace. The burning of fuel in the steam boiler 5 results in the generation of combustion gases, which are sent to the economizer unit 9 through the flue gas line 10. The water in the boiler flows from the steam drum 24 through the boiler water pipes, it absorbs the heat from the furnace and returns to the steam drum 24, where the saturated steam is separated from the boiler water.

Part of the saturated steam is fed through a second steam line 11 through three superheaters 12 arranged in series along the second steam line 11. The superheaters 12 are used to further increase the steam temperature to generate steam overheated. The superheated steam is then supplied to a suitable application, such as a steam turbine (not shown). In alternative embodiments, the steam boiler system may comprise any suitable number of superheaters. Some of the saturated steam flows from the steam drum 24 and through the first steam line 8 to the condenser 2. The feed water flowing through the condenser 2 absorbs the heat from the steam. The steam condenses and the condensate accumulates in a condensate tank 22 (see Figure 2).

The condensate tank 22 is connected to a spray water tempering unit 13 by means of a first condensate line 14. The spray water tempering unit 13 comprises two spray water tempering devices 13a, 13b. The spray water desuperheaters 13a, 13b are connected to the second steam line 11 between the superheaters 12 and are adapted to inject a coolant in the form of spray water into the superheated steam. The spraying water tempering unit 13 enables the temperature of the superheated steam to be regulated.

The first condensate line 14 has two branches for supplying condensate to the spray water desuperheaters 13a, 13b. Each branch is provided with a second regulating valve 16a, 16b to regulate the flow of condensate to the spray water desuperheaters 13a, 13b. A control unit 18 is coupled to the second regulating valves 16a, 16b and to three temperature sensors 17a, 17b, 17c arranged to measure the temperature of the superheated steam. The control unit 18 is adapted to control the second regulating valves 16a, 16b and, therefore, the flow of condensate through the first condensate line 14, depending on the temperature values received from the temperature sensors 17a, 17b, 17c.

[The condensate tank 22 is also connected to the steam drum 24 in the steam boiler 5 by means of a second condensate line 15. A first regulating valve 19 is connected to the second condensate line 15. The first regulating valve 19 is it couples to the control unit 18, which uses the first regulating valve 19 to regulate the flow of condensate through the second condensate line 15 and, therefore, the level of condensate in the condensate tank 22 (see Figure 2 ) based on the information received from a condensate level sensor 20 in the condensate tank and a temperature sensor 26 connected to the second feed water pipe 6 between condenser 2 and economizer unit 9.

Figure 2 is a schematic side view of the capacitor 2 of Figure 1, in which some parts have been removed for clarity.

Condenser 2 comprises a first compartment 21 connected to the first feed water line 3 and arranged to receive feed water from the feed water source 20 (see Figure 1). The condenser 2 further comprises a condensate tank 22 connected to the first steam line 8 and arranged to receive saturated steam from the steam drum 24 in the steam boiler 5 (see Figure 1). Condenser 2 also comprises a second compartment 23 connected to the second feed water line 6 to supply preheated feed water to the steam boiler 5 (see Figure 1). The first and second compartments 21, 23 are connected by means of the internal supply water supply system 7, which comprises a plurality of conduits, which extend through the condensate tank 22 and are adapted to supply supply water from the first to second compartment 21,23. The feed water from the first feed water line 3 flows to the first compartment 21 and from there through the internal feed water line 7 to the second compartment 23 and then to the second feed water line 6 The heat is transferred in the condenser 2 from the saturated steam to the feed water that flows through the internal feed water conduction system 7, thus preheating the feed water while generating condensate from the steam, which is collected in condensate tank 22.

The first condensate line 14 and the second condensate line 15 are connected to the bottom of the condensate tank 22. This arrangement allows the complete emptying of the condensate tank 22 and increases the scope of the condensate level.

The condensate level in the condensate tank 22 is measured by means of a condensate level sensor 20 (shown schematically). The condensate level sensor 20 is controlled by means of the control unit 18 (see Figure 1).

Next, a first embodiment of the method according to the invention will be described with reference to Figures 1 and 2.

The feed water is fed from the feed water source 4 to the first compartment 21 in the condenser 2 through the first feed water line 3. The feed water flows from the first compartment 21 to the second compartment 23 through the Internal feed water line system 7. The feed water is preheated as it flows through the internal feed water line system 7 by the heat transferred from the steam in the condensate tank 22. The feed water Preheated is guided through the second feed water line 6 to the economizer unit 9, where the feed water temperature is further raised by hot combustion gases from the furnace in the steam boiler 5. The Feed flows through the second feed water line 6 to the steam boiler 5 where it is collected in the steam drum 24. E The steam drum 24 supplies boiler water to the boiler water pipes (not shown) and the heat from the oven (not shown) evaporates some of the boiler water, after which the boiler water and the Steam return to steam drum 24 where the saturated steam is separated from the boiler water. Part of the saturated steam is supplied to one or more applications through the second steam line 11 and part of the saturated steam is supplied to the condensate tank 22 in the condenser 2 through the first steam line 8. The heat from the saturated steam is transfers from the steam in the condensate tank 22 to the feed water that flows through the internal feed water conduction system 7. The feed water thus acts as a refrigerant for the steam and the condensed steam is collected in the fuel tank condensate 22. Part of the condensate is supplied to the spray water tempering unit 13 through the first condensate line 14.

The rate of heat transfer in condenser 2 depends on the level of condensate in condensate tank 22. An increase in the level of condensate reduces the surface area of the internal feed water conduction system 7 exposed to steam while a decrease in the Condensate level increases the surface area of the internal feed water conduction system 7 exposed to steam. A higher condensate level results in a lower heat transfer rate, while a lower condensate level results in a higher heat transfer rate.

The control unit 18 uses the first regulating valve 19 in the second condensate line 15 to regulate the flow of condensate out of the condensate tank 22 through the second condensate line 15. That is, the level of condensate in the condensate tank Condensate 22 can be adjusted independently of the need for condensate in the spray water tempering unit 13.

The control unit 18 is coupled to the condensate level sensor 20 and to the temperature sensor 26 and continuously receives information related to the level of condensate in the condensate tank 22 and the temperature of the feed water in the second supply water line. supply 6. Control unit 18 controls the first regulating valve 19 based on this information. If the temperature sensor 26 registers a feed water temperature below a predetermined lower temperature (indicating that the feed water temperature is approaching or has reached a temperature that can cause corrosion damage to the economizer unit 9) , then the control unit 18 uses the first regulating valve 19 to increase the condensate flow through the second condensate line 15, resulting in a lower condensate level in the condensate tank 22 and an increase in the rate of heat transfer from steam to feed water. Similarly, if the temperature sensor 26 registers a feedwater temperature above a predetermined higher temperature (indicating that the feedwater temperature is approaching or has reached a temperature that may lead to the generation of steam in the economizer unit 9), then the control unit 18 uses the first regulating valve to reduce the flow of condensate through the second condensate unit 15 and to raise the level of condensate in the condensate tank 22, in order to reduce the rate of heat transfer from steam to feed water.

The control unit 18 is also adapted to ensure that the level of condensate in the condensate tank 22 remains below a predetermined maximum level. The maximum level may be, for example, at a level in which all or most of the internal supply water conduction system 7 is covered by condensate. When the condensate level reaches the maximum level, the control unit 18 can increase the condensate flow through the second condensate line 15. The control unit 18 can also be adapted to ensure that the condensate level in the condensate tank 22 remains above a predetermined minimum level, to ensure that the amount of condensate in the condensate tank 22 is sufficient to cool the superheated steam in the spray 13a, 13b. When the condensate level falls below the minimum level, the control unit 18 reduces the flow of condensate through the second condensate line 15.

Figure 3 shows a second embodiment of a steam boiler system 1 according to the invention. The main difference between the first and second embodiments of the first and second steam boiler system 1 is that the second condensate line 15 in the second embodiment is connected to the feed water source 4, so that the excess condensate in condenser 2 is returned to feed water source 4.

Figure 4 shows a third embodiment of a steam boiler system 1 according to the invention. The steam boiler system 1 of Figure 4 comprises an additional condenser 42.

The condensers 2, 42 are connected to the same first and second water lines 3, 6 and to the same first condensate line 14. The condensers 2, 42 are connected to the steam boiler 5 by means of the respective steam lines 8 , 48.

Condensers 2, 42 are also connected to a second common condensate line 15. The steam boiler system of Figure 4 further comprises two first regulating valves 19 to regulate the flow of condensate through the second condensate line 15 Regulating valves 19 are arranged in respective branches of the second condensate line 15. Each branch is connected to a respective condenser 2, 42, so that each first regulating valve 19 can be used to regulate the flow of condensate from a condensate tank. respective. The first regulating valves 19 are controlled by means of the control unit 18 based on the information received from the temperature sensor 26 and the condensate level sensors 20, 44.

Alternatively, in an embodiment not shown in the Figures, a steam boiler system may comprise two condensers connected to a second common condensate line, in which a single first regulating valve is arranged in the second condensate line common to control the flow of condensate from both condensers.

The person skilled in the art understands that the scope of protection provided by the claims is not limited to the embodiments described above. The embodiments can be combined and modified in many ways without departing from the scope of protection. For example, the control unit may comprise a plurality of separate control units, where one control unit is adapted to control the first regulating valve and the other control unit is adapted to control the second regulating valves. The second condensate line in Figure 1 can be connected to any suitable part within the steam condensate system and can incorporate two or more condensers.

Claims (8)

1. Steam boiler system (1) comprising: - a steam boiler (5) that generates steam from the feed water; - a condenser (2; 42) that transfers heat from said steam to said feed water; - a first feed water line (3) connecting said condenser (2; 42) to a feed water source (4) to supply feed water to said condenser (2; 42); - a second feed water line (6) connecting said condenser (2) to said steam boiler (5) to feed feed water from said condenser (2) to said steam boiler (5); - a first steam duct (8; 48) connecting said steam boiler (5) and said condenser (2; 42) to supply steam to said condenser (2; 42) from said steam boiler (5); - a condensate tank (22) arranged to collect the condensate generated from said steam in said condenser (2; 42); - a first condensate duct (14) connecting said condensate tank (22) to a tempering unit (13); further comprising said boiler system (1): - a second condensate duct (15) connected to said condensate tank (22) and directly to a steam drum (24) in said steam boiler (5) to feed condensate outside said condensate tank (22) and into said steam drum (24); - a first regulating valve (19) arranged to regulate the flow of condensate through said second condensate line (15); - an economizer unit (9) connected to the second feed water pipe (6) between said steam boiler (5) and said condenser (2; 42); - at least one temperature sensor (26) adapted to measure at least one parameter indicative of the temperature of the supply water in the second supply water conduit (6); - a control unit (18) adapted to control said first regulating valve (19) at least partially depending on the information collected by said temperature sensor (26); Y - at least one condensate level sensor (20; 44) adapted to measure at least one parameter indicative of the level of condensate in the condensate tank (22), - said control unit (18) is coupled to at least one temperature sensor (26) and at least one condensate level sensor (20; 44); said control unit (18) being adapted to control said first regulating valve (19) at least partially based on the information collected by said condensate level sensor (20; 44). 2. Steam boiler system (1) according to claim 1, said steam boiler system (1) comprising more than one condenser (2; 42). 3. Procedure for controlling a steam boiler system (1), said steam boiler system (1) comprising a steam boiler (5), a condenser (2; 42), a first feed water line (3 ) that connects said condenser (2; 42) to a supply water source (4), a second supply water pipe (6) that connects said condenser (2; 42) to said steam boiler (5), a temperature sensor (26) connected to said second feed water line (6) between the condenser (2) and the economizer unit (9) and connected to the control unit (18), a first steam line (8; 48) connecting said steam boiler (5) and said condenser (2; 42), a condensate tank (22), a first condensate line (14) connecting said condensate tank (22) to a tempering unit (13), and an economizer unit (9) connected to the second feed water pipe (6) between said steam boiler (5) and said count nsador (2; 42), said procedure comprising the steps of: - supplying feed water to said condenser (2; 42) through said first feed water line (3); - supplying feed water from said condenser (2; 42) to said steam boiler (5) through said second feed water pipe (6); - using said steam boiler (5) to generate steam from said feed water; - supplying steam from said steam boiler (5) to said condenser (2; 42) through said first steam line (8; 48); - using said condenser (2; 42) to transfer heat from said steam to said feed water to preheat said feed water and generate condensate from said steam; - collecting said condensate in said condensate tank (22); in which a first regulating valve (19) is coupled to a control unit (18), said control unit (18) uses the first regulating valve (19) to control a flow of condensate from said condensate tank (22) and towards a steam drum (24) in said steam boiler (5) through a second condensate line (15) connected to said condensate tank (22) and directly to said steam drum (24) and, therefore, the level of condensate in the condensate tank (22) is a function of the information received from a condensate level sensor (20) in the condensate tank (22) and from a temperature sensor (26); wherein the rate of heat transfer in the condenser (2; 42) depends on the level of condensate in the condensate tank (22). 4. Procedure according to claim 3, said procedure comprising the steps of: - continuously measure at least one parameter indicative of the temperature of the feed water in the second feed water line (6); Y - controlling said first regulating valve (19) at least partially as a function of said measurements. 5. Procedure according to claim 4, said procedure comprising the steps of: - continuously measuring at least one parameter indicative of the level of condensate in said condensate tank (22); Y - controlling said first regulating valve (19) at least partially as a function of said measurements. 6. Method according to any one of claims 3-5, comprising the step of regulating the flow of condensate through said second condensate conduit (15) to ensure that the temperature of the feed water at a specific point in the second feed water line (6) is maintained above a predetermined lower temperature. 7. Method according to claim 6, comprising the step of regulating the flow of condensate through said second condensate line (15) to maintain the temperature of the feed water at said specific point in the second water line of feed (6) below a predetermined upper temperature. The method according to any one of claims 3-7, comprising the step of regulating the flow of condensate through said second condensate line (15) to ensure that the level of condensate in the condensate tank (22 ) stays within a predetermined range.